Electrical conductor



C. A, PARSONS ET' AL,

ELECTRICAL CONDUCTOR 'Filed Nov. 9A i925 2 Sheets-Sheet /M/EN ma; @Mamas QmsM/S gieen. 2651# Patented Jan.y 3, 1928s l,55,l06l

ELECTRICAL CONDUCTOR.

Application led November 9, 1925, Serial No. 68,037, and in Great Britain December 28, 1924i The present invention relates to electrical conductors and particularly to those of a flat elongated form suitable for the slot windings of dynamo-electric machines.

With a view to eliminating eddy-current losses in such conductors, they have been commonly built up of a large number of comparatively small helically-disposed insulated strands. In order to make the best possible use ofthe space available for such conductors, the insulation on the individual strands has necessarily to be very thin and owing to the danger of adjacent wires overriding, and to the pressure to which the conductors are subjected in the course of manufacture it is found in certain circumstances that the insulation breaks down, thereby causing contact between adjacent conductors anda consequent loss of efficiency.

The object of the present invention is to overcome difoulties of the nature pointed out above.

With such an object e present invention consists in the features of novelty hereinafter fully described and pointed out in the claims.

Referring to the accompanying diagrammatic drawings:-

Figure 1 shows a side elevation of one form of machine according to the present invention in which insulating material is introduced by way of a. hollow core,

Figure 2 being a cross section on the line 2-2 of Figure 1, looking in the direction of the arrows;

Figure 3 showsa perspective view to an enlarged scale of part of the hollow core with tongue for securing it in place;

Figure 4 shows a side elevation of a modified form of machine having a solid dummy core, and

Figure 5 a detail of another modification, inl which two strips of insulation are used, while finally Figure 6 shows a perspective view to an enlarged scale of a flat elongated conductor with interposed insulation according to the present invention,

Figure 7 showing'a cross section also to an o enlarged scale of a conductor having additional insulated layers.

The same reference symbols are used in the different drawings to denote correspondlng parts.

In carrying the Iinvention into effect according to the illustrative form shown in igures l and 2, a modication of the machine described in the specification of Britall the essential parts of the machine therein described, including the revolubly-mounted reels, a, carrying the individual strands, b, the die-plate, c throat-piece, d, adjustable rolls, e, and so forth, the dummy core, f for t e manufacture of the conductor o an elongated or flat cross section, as shown for example in Figure 6, is modified by being. constructed of a hollow form and insulation, 7i, of a suitable deformable material in strip or tape form is passed through the hollow core into the centre of the helically-disposed strands, b, the whole being then subjected to pressure by the adjustable rolls, e.

n Figure 1, the end of the dummy core from which the insulation emerges is indicated at f.

The dummy core, f, may be convenientl constructed as shown in Figure 3, i. e., with a tubular portion, f2 and an integral tongue, f3, for attachment to the stationary manrel, g.

lVth suitable material it is found in practice that the insulation so treated oozes u between the strands themselves and fills the interstices between them. Under the proper conditions this action maybe so effective that the copper strands themselves as drawn from their reels may be uninsulated.

According to the nature of the material used. the insulation so added may deform to a sufficient extent only partially to fill the interstices as seen in Figure 6, but the action aimed at in every case is to add insulation with the minimum increase in the dimensions of the conductor as a whole.

In a modified form of the machine described above, (see Figure 4) the dummy core, 7s, may be made of flat form as before and the insulating strip, it, fed over its surface to the interior of the stranded conductor, as shown.

By treating the first two layers of the stranded came, e. g.

the two layers shown in Figure 6, as a core for additional layers, insulation can be inserted in this manner beneath each additional layer as it is helically laid in place, so as to build up a conductor, for example, as shown in Figure T, the preferable arrangement in such a case being that two strips of insulation are simultaneously inserted one on each side of the basic stranded core. Thus as shown in Figure 5, the two strips of insulation are indicated at h, h', and the basic core which takes the place of the original dummy core, at m.

The function of such a core in each case is to determine. the shape of the conductor and to act as a member resistant to the stresses imposed by the helical laying of the wire strands, the insulating material owing to its deformability or plasticity being incapable of performing such functions.

It will be seen that the processes of manufacture according to the present invention are continuous, the operations of helical stranding and introduction of insulating material proceeding simultaneously.

The insulating material may be of any degree ofdeformability, ranging in different cases from the micaceous or fibrous to the plastic or even liquid state, pressure being used if desirable,

An electric conductor manufactured according to the fundamental principle of the present invention is highly efficient as reards the insulating from one another of the individual strands while at the same time the latter receive additional mechanical protection.

Although the invention has been specially devised for the manufacture of electrical conductors of the elongated cross section described, it is nevertheless applicable to other forms of cross section while in addition the details of the processes and machines described can be varied Without departing from the underlying principle of the invention.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is

l. -A process of manufacturing electrical conductors having a plurality of faces, consisting in juxtaposing deformable insulation in layer form in longitudinal relation to a resistant shape-determining member having faces similarly disposed to those of the finished conductor; helically laying around said shape-determining Amember and said juxtaposed insulation a series of wire strands; and separating said shape-deter mining; member and said strands so laid.

2. A process of manufacturing electrical conductors having aplurality of faces, consisting in `iuxtaposing plastic insulation in layer form in longitudinal relation to a resistant shape-determining member having 'ber and said strands so faces similarly disposed to those of the finished conductor, helically laying around said shape-determining member and said juxtaposed insulation a series of wire strands and subsequently applying external pressure to locate finally said series of wire strands and to force said plastic insulation into the interstices therebetween.

A process of manufacturing electrical conductors having a plurality of faces consisting in juxtaposing deformable insulation in strip forni in longitudinal relation to a resistant shape-determining member having faces similarly disposed to those of the finished conductor; helically laying around said shape-determining member and said juxtaposed insulation a series 0f wire strands; and separating said shape-determining member and said strands so laid. I

1. A process of manufacturing electrical conductors having a plurality of faces, consisting in progressively 'uxtaposing deformable insulation in strip form in longitudinal relation to a resistant shape-determinin member having as many faces as the finishe conductor; helically1 laying around said shape-determining member and said juxtaposed insulation a series of wire strands; and separating said shape-determining memlaid.

5. A process of manufacturing electrical conductors having a plurality offaces, consisting in simultaneously juxtaposing strips of deformable insulation in longitudinal relation to a resistant shape-determining member having as many faces as the finished conductor; helically laying around said shape-determining member and said juxtaposed insulation a series of wire strands; and separating said shape-determining memf ber and said strands so laid.

6. A process of manufacturing electrical conductors having an oblong cross-section consistingin sliding insulation material longitudinally along a resistant shape-determining member likewise having an oblong cross section; helically laying around said shape-determining member and said juxtaposed insulation a series of wire strands; and separating said shapeLdetermining member and said' strands so laid.

7. An additional step of the process claimed in claim 6, according to which the conductor manufactured as set forth in claim 6, itself forms a resistant shape-determiningmember for the super-position thereon of additional separate strips of insulation juxtaposed longitudinally one strip on each wide face of said member and an additional helical series of wire strands laid therearound.

8. A process of manufacturing electrical conductors as claimed in claim 6, in which the insulation is of a plastic nature and in which the electrial conductor manufactured as set forth in said claim 6 is submitted suicient pressure finally to cally-laid wire strands to locate said helimember is hollow an is slid therethrough.

d the insulaton'material ,and to cause said In testimony whereof we have signed our Eastic material to lill the interstices therenames to this specification.

tween. CHARLES ALGERNON PARSONS. 9. A process of manufacturing electrical JESSEL ROS N. conductors as claimed in claim 6, according ARTHUR WALLACE GREY. to` which the resistant shape-determining BENJAMIN BLAIR. 

